1. Field of the Invention:
The present invention relates to an indication device of photographing information of a camera, particularly relates to an indication device for shutter time and diaphragm aperture.
2. Description of the Prior Art:
As a convenience for photographers, view finders of cameras often display various types of photographic data. If the diaphragm aperture is displayed, the photographer can readily estimate the depth of field. If the shutter time is displayed, the photographer can easily determine whether moving objects can be photographed. Therefore, cameras having information indicating view finders are widely used.
Many types of single-preference automatic exposure control (AE) cameras are available. In the shutter preference type, the shutter speed is selected and the diaphragm is automatically set to conform to the shutter speed. Conversely, in the diaphragm preference types, the diaphragm is selected while the shutter speed is automatically adjusted thereto. Double preference cameras in which either the shutter speed or the diaphragm may be set while the other is automatically adjusted thereto, have been proposed. Such cameras can utilize a conventional method of mechanically indicating the preset values of shutter time or diaphragm aperture with an indication member. They can display both automatically adjusted values with the same meter movement by mechanically switching between a shutter scale and a diaphragm scale. Such conventional devices are somewhat confusing and inconvenient for a photographer when the preference mode is switched. The system is also mechanically complicated and adds weight to lightweight cameras. One proposal for eliminating these shortcomings involves the use of a seven segment LED indicator for digitally indicating the preset value and the automatically adjusted value. However, the digitally indicated shutter time follows a primary geometrical progression such as 8, 4, 2, 1, 1/2, 1/4, . . . When intermediate values are indicated they can be appreciated intuitively. Diaphragm values follow a secondary geometrical progression such as 1, 1.4, 2, 2.8, 4, 5.6 . . . Even if intermediate values are indicated, their effect is more difficult to appreciate.
In this case, since the shutter time digitally indicated is such primary geometrical progression series as 8, 4, 2, 1, 1/2, 1/4, when intermediate values therefor are indicated, they will be apprehended intuitively, but as the diaphragm values are such secondary geometrical progression series as 1, 1.4, 2, 2.8, 4, 5.6 . . . . . , even if the intermediate values therefor are indicated, they will be hard to be apprehended. From the above, it will be understood that digital indication is convenient for shutter time but not suitable for diaphragm value indication.